Nature as Teacher:

Ecosystem Characteristics Applied to Urban Settings

Tiffany Tong

November 15^th, 2006

Treat the earth well: it was not given to you by your parents; it was loaned to you by your children. We do not inherit the Earth from our Ancestors, we borrow it from our Children.”

Ancient Indian Proverb

Introduction

The earth’s condition has been deteriorating since the industrial revolution (Hails). Global warming, pollution, peak oil, ozone layer depletion and many others have become household terms. The most famous international environmentally friendly protocol, the Kyoto protocol, has been signed for 8 years. Yet, not only has Canada failed to meet its goal of reducing 6% of carbon dioxide emissions from the 1990 level, but instead, is has actually gone up 24% (CBC News). Our current ecological footprint analysis tells us that for everyone in the world to live a Canadian lifestyle-that is with large sprawling urban areas and more than one car per family-we need the total resources of 4.2 Earths (the ecological footprint per capita in Canada is 7.6 hectares when the biocapacity is 1.8 hectares) (Hails). Although words such as sustainability or ecological footprint are tossed around, by most people, casually and without real meaning, I believe it has come to a time when these terms should be treated by all with serious respect and, accordingly, take action to help prevent a global crisis happening. Where should we start? By thinking and being sustainable.

Sustainability is very hard to define. The formal but vague definition from the 1987 Brundtland Report, defined sustainable development as development that “meets the needs of the present generation without compromising the ability of future generations to meet their own needs,” which is hard to evaluate using statistics (Brundtland et al). However, there is one indicator that can give us an idea of whether we are within the limits of sustainability or not. Energy. All energy on Earth comes either directly or indirecty from the sun. Therefore, if the energy consumption of all life forms is more than the energy output of the sun, meaning that we are using more than what the earth can assimilate, then we are unsustainable (Graham 148). As the energy consumption level of almost all organisms except for humans is usually constant, the change in human energy consumption affects the total energy consumption directly (Brandon and Lombardi 27)

The biggest problem we are facing now is that we are spending more energy than the output of the sun, thus we humans, as a whole, are living unsustainably (Graham 149). The Earth cannot assimilate all our extra carbon production (from our over use of energy) and therefore many problems, such as extinction of species, arise. How should we deal with this problem? By starting at the single biggest energy consumption of the modernized city: the construction and maintenance of buildings (Kibert 11; Graham 35).

Learning from Ecosystems

One might ask, why is the energy consumption of buildings the largest of all? The reason lays in the design of our buildings. As the idea of “green buildings,” defined as designs that transform matter and energy using processes that are compatible and synergistic with nature and modeled on natural systems, is fairly recent (Kibert 109). Most of our present buildings are designed without any ecological impact consideration in mind (Kibert109). They were constructed as if the city is separated from the ecosystems around it, that the building should be a totally artificial domain where natural laws do not work (Graham). We have forgotten that our cities are also part of the whole biosphere where interactions between ecosystems are inevitable. At present, 2% of the world’s land surface is covered by cities and yet the people living in them consume 75% of the resources consumed by mankind (Hui). Therefore, to improve our designs, we must learn from ecosystems and incorporate our findings into our building designs. Although ecosystems differ greatly among regions, the points below are most common features of most ecosystems.

The higher the genetic, species, habitat, niche diversity, the higher the resilience

Resilience is defined as the ability of an ecosystem to maintain its functions while coping with change (Graham 106; Brandon and Lombardi 28). Genetic diversity within a species prevents complete wipe out of the species when environmental changes occur. Likewise with species diversity which provides an alternate pathway if one species is extinct. Habitat diversity refers to the different physical environments inside an ecosystem (Graham 106). And niche diversity is the number of specialized relationships that occur between organisms and their habitat (Graham 106). The increase of diversity raises the resilience because it creates “buffer zones” in which impacts of the environment can be absorbed (Graham 107).

This characteristic of ecosystems can be applied to the urban setting by designs that allow close interaction with nature without causing harm. An increased level of mixed land use, which has been proven to have a smaller ecological footprint than normal buildings with only one use (Norman et al), will also contribute to increased resilience (Graham 107). Change in the environment, such as climate, or invasion of species or diseases, is inevitable, therefore the more resilience we have, the more change we can adapt to.

Constant feedback of energy and matter between organisms and their environment

Ecosystems evolve and survive because of constant cycling of energy and matter. From the nutrients in the soil grows plants, which are consumed by animals, which are then passed out of the animal’s system and fungi or bacteria decompose the matter back to nutrients. No matter is “wasted.” (Graham 107; Brandon and Lombardi 27)

Buildings should also find ways to use materials that can be recycled back into the natural environment within a short period of time, Wastes that are produced should be assimilated as soon as possible; the continual accumulation of wastes should be avoided, like the present landfills.

Moves up a hierarchical staircase of biodiversity

Left to their own device, ecosystems tend to move from an immature stage, which has little biodiversity, to a mature stage, where the diversities become sophisticated, over a long period of time (Graham 108). The niche diversities in any mature ecosystem increases the carrying capacities, because more species of organisms can be involved with the matter and energy cycling process (Graham 108).  Instabilities in the ecosystem due to environment or species variation are also reduced (Graham 109).

The future city designs should take in consideration of helping both the surrounding and internal ecosystems to move up the hierarchical staircase by protecting and letting the biodiversity evolve naturally. This is essential for maintaining the ecological carrying capacity required to accommodate human activities that are damaging to the natural ecosystem (Brandon and Lombardi 29; Graham 204). For example, wastes produced and raw materials extracted from the environment need to be assimilated and regenerated by the surrounding ecosystems.

Resources are consumed at a rate equal to or less than at which they can be replenished

The first law of thermodynamics (the law of conservation of energy) dictates that to do work, energy has to be transferred from an “useful” state to an “useless” state. Therefore to maintain a sustainable environment, resource consumption and waste have to be minimized and efficiency of energy use has to be maximized (Graham 144). Natural selection “chooses” the most efficient species over a period of time, thus as the ecosystem matures, the organisms become more and more efficient and so the same energy can support an increasing number of organisms. In other words, the carrying capacity is increased.

As our surroundings, both biotic and abiotic factors, change constantly, our cities, like nature, will have to “evolve” continuously to accommodate the different requirements. The buildings and cities we have now are highly inflexible, meaning they are not designed to absorb any change without large inputs of energy such as demolishing and rebuilding the whole building (Kibert 181; Graham 62). We need to find new ways to construct buildings that can easily adjust to varying natural conditions, such as weather or humidity. For example, some types of designs are called “passive housing,” where the design allows the building to “default to nature (Kibert 186).” A good passive design uses the natural resources of the site, such as sunlight, wind, and vegetation, to the maximum, so that less external energy needs to be inputted (Kibert 186). Each passive design is specifically accustomed to a certain landscape and climate (Kibert 186); similar to ecosystems being particular to a certain environment.

Uses only solar energy to restore high entropy to low entropy

In natural ecosystems, there is no other energy source other than the sun; therefore it is natural that the ecosystems evolved to only use solar energy. Solar energy is described as “stock-abundant but flow limited” which means there is an endless (at least to most natural processes) supply of energy, but the amount supplied each day cannot be increased (Graham 138).

On the contrary, modern human societies have started using large amounts of terrestrial energy resources like crude oil and coal which are “stock limited but (temporarily) flow abundant (Graham 140).” This over usage cannot continue on forever because there is a finite supply of terrestrial energy, and when all is used up, there is no way to rapidly produce more energy to restore the high entropy of the earlier reactions. Therefore, to be truly sustainable, we have to design our buildings to use only renewable energies such as solar energy and wind power that are “stock abundant” to move our processes (Graham 140).

Positive feedback loops that recycle “wastes”

Surviving natural ecosystems have evolved to use “autocatalytic feedback designs,” where the consumption of energy in one process becomes a catalyst for the production of more energy in another (Graham 144). Simply put, the “waste” or one metabolic process is the inputting “resource” or “raw material” of another. Therefore the output of consumption, “waste,” has to be non-toxic to the system and easily reused without the addition of more energy (Graham 145).

Buildings also have to “evolve” to include autocatalytic feedback designs in both artificial and natural processes. It should be ensured that the energy needed to run the positive feedback loop is less than the energy produced in the product (Graham 145). Otherwise, the overall process will be unsustainable, since input of energies is needed. We have to make sure that the end products of the artificial processes is not toxic and can be used as an input material to the natural environment.

Energy is used in a large number of small steps

Using a staircase as an analogy, a staircase with large drops will reach the destination very soon and can only have a few number of steps; however, a staircase with many small drops and support many more steps and will take a long time to reach the end. In natural ecosystems, the breaking down of material and energy is separated into many small steps where each step supports different life forms (Graham 143). The energy value is maximized so the ecosystem can increase its carrying capacity and support as many organisms as possible (Graham 143).

Building design should follow this characteristic of natural ecosystems to ensure the longevity and dynamicity of our artificial system. The reason why our current cities cannot support our population in sustainable ways is because the “staircase with large drops” approach is used (Graham 144).

Conclusion

The natural ecosystems around the world have evolved for many millions of years to adapt to specific environments. They contain the wisdom of nature on how to maximize carrying capacity without harming the surroundings. Once we shift our perspective of humans as an individual biosphere separated from nature by machines and technology to humans being a part of the larger biosphere, we can start seeing the ingenuity of the designs of nature. If we can learn from these designs, modify them to suit our purposes, and apply them to building our cities and constructing our buildings, then we have taken a huge step in the direction of becoming sustainable. To preserve the biodiversity of the world, we must take action before we destroy the natural environment to such an extent that it is almost impossible to learn from it.

Works Cited

Brandon, S. Peter, and Patrizia Lombardi. Evaluating Sustainable Development in the Built Environment. Massachusetts: Blackwell Science, Inc., 2005.

Brundtland, Gro Harlem et al. “Report of the World Commission on Environment and Development: Our Common Future.”  1987. <http://www.are.admin.ch/imperia/md

/content/are/nachhaltigeentwicklung/brundtland_bericht.pdf?PHPSESSID=076b7b20f63b36f962a1467ce64e6898> (cited Nov. 15, 2006)

Bunz, Kimberly R., Gregor P. Henze, P.E., and Dale K. Tiller. “Survey of Sustainable Building Design Practices in North America, Europe, and Asia.” Journal of Architectural Engineering. 12.1 (2006)

CBC News. October 11, 2006. “In Depth: Kyoto and beyond Canada-Kyoto timeline.”

<http://www.cbc.ca/news/background/kyoto/timeline.html> (cited Nov. 14, 2006)

Graham, Peter. Building Ecology: First Principles for a Sustainable Built Environment. Massachusetts: Blackwell Science, Inc., 2003

Hails Chris. World Wildlife Fund (2006). “The Living Planet Report 2006” <http://assets.panda.org/downloads/living_planet_report.pdf> (cited Nov. 14, 2006)

Hui, Sam C. M. (2000) Low Energy Building Design in High Density Urban Cities.

<http://www.arch.hku.hk/~cmhui/wrec6d.pdf> (cited Nov. 14, 2006)

Kibert, J. Charles. Sustainable Construction: Green Building Design and Delivery. New Jersey: John Wiley & Sons, Inc., 2005

Norman, Jonathan, Heather L. MacLean, M.ASCE, and Christopher A. Kennedy. “Comparing High and Low Residential Density: Life-Cycle Analysis of Energy Use and Greenhouse Gas Emissions.” Journal of Urban Planning and Development. 132:1 (2006)

(This was my Science One Literature Based Research Project)